If Speedfan had the ability to periodically reassert the fan speed commands, say once every several minutes, the fan speeds would recover to the desired levels following sporadic temperature spikes.

Steps To Reproduce

With this particular motherboard's BIOS, HP removed the ability to kill the BIOS CPU temperature control. What happens is that the CPU temp will occasionly spike to over 75C and return immediately to previous temerature. (Probably a bad reading since it never stays that high.) This causes the fan speed to max out and then immediately return to the BIOS's lowest fan speed setting. All of this happens too fast for Speedfan to see the temp spike and thus it continues to sit at its fan speed command level never noticing that the actual fan speed is much different from the desired setting since it has no actual fan speed feedback.

Additional Information

For example I have found that running the two fans at 65% and 50% as minimum settings generally keeps the CPU around 55C. These settings give a speed reading of 3000RPM and 1100RPM. When the BIOS sets its lowest speed, the fan speeds end up at 2000RPM and 950RPM. The speeds stay there until Speedfan finally sees a temperature reading greater than its setpoint and starts asserting the commands to the fans again. Usually this doesn't happen for hours.

SpeedFan does not rely on reported fan speeds, but only on temperatures. By fine tuning fan speed settings you can achieve your goal. For example: you might set MAX SPEED to 65% and 50%. SpeedFan will never go higher, unless WARNING temps are exceeded. By playing with these settings you might do what you need.
The intervention from an external software (BIOS) is something that SpeedFan can't fight. It is assumed that there is no other tool acting on SPEEDs. But this is not causing any realy harm as SpeedFan keeps monitoring temperatures and rises fan speeds accordingly.
As a final note: please enter CONFIG / ADVANCED. There might be an option to set fan speeds to MANUAL, thus achieving what BIOS no longer allows you to.

I understand what you are saying and you are right there is really no harm being done in this case because if the temperature goes over the setpoint, Speedfan sends a new command to the fan and the speed changes to bring the temperature down.

Alfredo, before I start let me say that what follows is my interpertation of what is going on internally in Speedfan. I realize I may be wrong in some aspects but I am basing this interpertation on what I am seeing as well as my experience in programming machine control software.
Kevin

That being said, I have seen the following occur. If Speedfan is asserting a 100% speed trying to bring the temperature down and the BIOS lowers the speed, Speedfan will not reassert the fan speed command because it is already at the max speed command setting.

A specific example I just had happen:

The CPU setpoint is 60C, the temperature increased above that and Speedfan brought the fan speed up to 100% which is right. However, before the temperature got down below the 60C setpoint, the BIOS brought the fan speed down to its low setting which in my case is actually less than the minimum speed setting I have. The BIOS happens to react very quickly to temperature changes and spikes, most of which I suspect are noise in the readings. Anyway, this causes the CPU temperature to stop decreasing and it stays above the 60C setpoint. Speedfan sees the temperature as still above the setpoint of 60C, looks at its command level of 100% and since there is no command change required, does not reassert the command to the fan. So the fan speed stays low, the CPU temp stays high and we are stuck there until either the CPU temperature drifts below the 60C, not likely, or the CPU temperature rises to the temperature level for the BIOS control to kick in again which raises the speed. If that happens I suspect that Speedfan will never really regain control as the BIOS will keep the CPU temperature cycling between it upper and lower settings (75C and 70C in my case). So my thought is that with a periodic resending of the fan speed command, Speedfan would regain control because the fan speed would rise back up to the 100% speed because the CPU is above the 60C setpoint, drive the CPU temperature down below the setpoint and be back in control.

I have this exact problem; it's a real pain when running 3D games, for example, since the high temperature causes my system to slow down. Even if it doesn't make sense to try and fight the BIOS in general (although I reckon there's some cases where it would still help) it would be really good to be able to force/reassert 100% fan speed for this very situation. Also note for reference bug 0000327, which could possibly be alleviated by this fix.